The answer to your question is, yes, he did destroy the devil. He did it ultimately on the cross but more importantly, he did it every day by virtue of his sinless life. He destroyed the "devil" in its place of residence, the human heart. The devil is not a fallen super-being bent on man's destruction. The devil is, in fact, "sin in the flesh."
Here are some initial points to consider:
In the Bible the point of origin of sin is always described as the flesh or the world. Who is the “Prince of this world” (cp John 12:31; Eph 2:2,3). It is sin which has reigned with the power of death (Romans 5:21; 6:16)
How did Christ’s sacrifice accomplish this end? Righteousness is granted by faith that God will heal us from the effects of sin when we recognize His just punishment for sin (especially our own) and we recognize Him as our sovereign Lord. We then leave the service of sin and enter the service of God. That means obedience to His will. The sign of that new allegiance and the first step in obedience to our new Master is baptism. cp. Genesis 3:15; John 12:31,32; Romans 3:23-26; Romans 6:4,16. Also, I would like to direct your attention to two of the titles in the "Library" section of the site:
God bless and keep you,